It is generally recognized that dicyclic naphthenes found in the high boiling portion of a wide cut naphtha fraction are undesirable components for processing in a platinum reforming operation. That is, under the standard reforming operation the high boiling dicyclic naphthenes dehydrogenate to form naphthalenes which age the reforming catalyst. In addition they raise the end boiling point of the product, lower its smoke point and in general degrade the burning quality of the liquid naphtha product.
In the prior art, one way of eliminating naphthalenes is to prevent their formation from the precursor dicyclic naphthenes by cutting the end point of the charge naphtha below that of decalin, i.e., about 370.degree.-380.degree.F. true boiling point (T.B.P.) of trans-decalin 369.degree.F., cis-decalin 384.degree.F., naphthalene 424.degree.F. However, cutting the naphtha at this low end point for the reforming operation necessarily reduces the net volume of desired reformed gasoline product.
The present invention is directed to a processing combination which increases the yield of desired octane full range gasoline product without increasing the undesired naphthalene content thereof.